The problem with April Fools is that a lot of the original joke ideas ended up becoming things people actually wanted, so when they turned out to be jokes, the community got uber butt mad.

Now, the April Fools jokes are obvious, but incredibly humorous and poke fun at the game and the community. I remember one year where if Mages counterspelled a Paladin it automatically respecced him to Holy, and if he already was Holy, it turned him into a Priest.

It's not tri-spec. Blizzard likes to "over-do" it. The never do anything believable, that's what makes them really funny. The bard class in itself is believable, but Blizzard just goes and overdoes it with the whole "guitar hero" gameplay. Tri-spec is something that is believable, and I can't really think of a way they can overdo it to make it funny.